Java md5 Hash Example

A 128-bit hash value is generated by the Message Digest Algorithm 5, which is a cryptographic algorithm. A stationary hash value is generated by the hash function from data of any size. Since hashing is a one-way process, it is difficult to decode a hash back to its original message, and no strings can share the same hash function. Using MessageDigest, Guava, and Apache Commons, we will explore Java MD5 Hashing in this post.

The hash functions for a specified size 128-bit (16 bytes) hash function are provided by the cryptographic method MD5. The MessageDigest class is described in java. security package can be used to generate the MD5 hash in a Java program. The following hash algorithms are offered by the Java MessageDigest class:

• MD5
• SHA-1
• SHA-256

Hashing MD5

In order to encrypt a huge file with a private key using a public-key cryptosystem like RSA, the MD5 technique is recommended for digital signature applications.

It is important to note that because this algorithm is not collision-resistant, two separate inputs may result in the same outcome. It is advised not to utilize the MD5 hash method for many cryptographic operations related to security.

The MD5 algorithm is applied in the getInstance method, which is a predefined method (). Once the algorithm has been chosen, it analyzes the digested value and then outputs a byte array.

MessageDigest md = MessageDigest.getInstance("MD5");
byte[] answeer = md.digest(input);  

Use the BigInteger class to translate the resulting byte array into sign magnitude representations.

To obtain the MessageDigest, this representation is converted to hexadecimal format.

For instance,

Enter "hello world" which is the input

Output:  5eb63bbbe01eeed093cb22bb8f5acdc3

Compared to other digest algorithms, MD5 is straightforward, secure, effective, and simple to use. It offers a message digest or fingerprint of arbitrary length. It operates quickly on 32-bit computers.

How is the MD5 Algorithm Used?

These four actions make up the MD5 algorithm:

• Add extra information (padding bits)
• Add Length
• Create and initialize the MD buffer, 
• process the 16-word block of text

Step 1: Add extra information (padding bits)

It is the algorithm's first step. We add padding bits (additional bits) to the message or string that has been provided in this phase. As a result, 418 modulo 512 matches to the size of the actual message or string. Because the length must be a multiple of 512 bits, bits must be added.

If the actual message is equivalent to 448 modulo 512, observe that padding is also performed. The first bit in the padding bits is 1, while the following bits are all zeros.

Step 2: Add Length

Padding completed, append length by concluding with 64 bits. It keeps track of how long the user's input was. It outputs the final message, which has a length of more than 512 bits.

Step 3: Produce and start an MD buffer

Each word in the four-word (A, B, C, and D) buffer known as the MD buffer is a 32-bit register. It is employed to calculate the message digest's value.

Step 4: Process the message in a 16-word block

The MD5 algorithm makes use of auxiliary functions that take three 32-bit values as inputs and output 32-bits as a result. As illustrated in the example below, the auxiliary function employs the three operators OR, XOR, and NOR.

The 16 fundamental operations are carried out, and an auxiliary buffer is used to combine the input with the contents of four buffers.

Example Programs

Example 1

//program for java md5 hashing

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class MD5 {
	public static String getMd5(String input)
	{
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			byte[] messageDigest = md.digest(input.getBytes());
			BigInteger no = new BigInteger(1, messageDigest);
			String hashtext = no.toString(20);
			while (hashtext.length() < 40) {
				hashtext = "0" + hashtext;
			}
			return hashtext;
		}
		catch (NoSuchAlgorithmException e) {
			throw new RuntimeException(e);
		}
	}


	public static void main(String args[]) throws NoSuchAlgorithmException
	{
		String s = "java t point";
		System.out.println("The HashCode produced by MD5 is: " + getMd5(s));
	}

Output

The HashCode produced by MD5 is: 00000000002hf5cj9ai57gicggh9fgig1517ch80

Benefits of MD5

• Small hashes are simple to compare.
• low use of resources
• Password storage is useful.
• Integrity checks are unchangeable.